Woohee murdered her 1st husband - the father of her child, and made her life objectively worse than what it was before he killed her husband. Woohee isn't entitled to her devotion and feelings just because he loved her more than the 1st husband did - thats entitlement. Now she and her son are essentially trapped hostages. And her son was denied the chance of not only knowing his real father but also his birthright linked to real lineage being raised by the man who murdered his father and forced his mother into a marriage because of it.
Are you going based on the novel or webtoon?
From what i understand the novel never confirmed paternity of the child - leaving up to the reader. The webtoon seemed to drift from that.
In the webtoon, The child has a birthmark the same as her 1st husband thats something even the FL confirms when bathing the child. What rapist are you referring to?

She’s super weird. Jinya doesn’t deserve Woohee. She’s always complaining about not having freedom and always being bound by duties. Her husband Woohee keeps telling her to just be herself stop caring about everything. Woohee is super honest also lol the dude is always straight to the point. Honestly I prefer Woohee over Jinya a lot. FLs character is just annoying.